In 3rd Generation Partnership Project Long Term Evolution (3GPP LTE), Orthogonal Frequency Division Multiplexing (OFDM) is adopted as a downlink (DL) transmission scheme. A 3GPP LTE communication system includes a DownLink (DL) that conveys signals from a Base Station (BS or NodeB) to User Equipments (UEs), and an UpLink (UL) that conveys signals from UEs to a NodeB. A NodeB transmits data information to a UE using a Physical DL Shared CHannel (PDSCH) and transmits DL Control Information (DCI) to a UE using a Physical DL Control CHannel (PDCCH). A UE transmits data information to a NodeB using a Physical UL Shared CHannel (PUSCH) and transmits UL Control Information (UCI) to a NodeB using a Physical UL Control CHannel (PUCCH).
UCI may include Channel State Information (CSI), which may include Channel Quality Indicator (CQI) information and Precoding Matrix Indicator (PMI) information. The CSI informs a NodeB of DL channel conditions that a UE experiences, and accordingly, the NodeB may select appropriate parameters, such as a transmission power, a Modulation and Coding Scheme (MCS), and any other similar and/or suitable parameters, for a PDSCH or PDCCH transmission to the UE and may ensure a desired BLock Error Rate (BLER) for transmitting respective data information or DCI.
A UE measures CSI based on a DL Reference Signal (RS) transmitted from a NodeB. Different CSI processes may be associated with different CSI measurements that may be respectively obtained from different RSs or from a same RS at different parts of a DL BW. The CSI may be transmitted in a PUCCH or in a PUSCH. The CSI transmission in a PUCCH may be semi-statically configured by a NodeB so as to occur periodically or may be dynamically triggered by a NodeB, i.e., the CSI transmission in PUSCH is an aperiodic CSI, through a “CSI request” field in a DCI format conveyed by a PDCCH scheduling the PUSCH transmission and it may support large CSI payloads in order to provide the NodeB with detailed information for PDSCH scheduling.